The invention relates to a current stabilizing arrangement comprising a first circuit between a first and a second power-supply terminal which comprises a series arrangement of a first resistor, a second resistor, and the collector emitter path of a first transistor whose base is connected to a point between the first and the second resistor, and a second circuit between a third terminal and the second power-supply terminal which comprises the collector-emitter path of a second transistor of the same conductivity type as the first transistor, whose base is coupled to the collector of the first transistor.
Such an arangement is suitable for general use in integrated circuits. In particular, such a circuit arrangement may be used in a one-chip integrated radio receiver.
Such a circuit arrangement is known from U.S. Pat. No. 3,831,040. In this arrangement the current in the first circuit is the unstabilized current and the current in the second circuit is the stabilized current. Stabilization is achieved by having the current in the first circuit, which can be adjusted by means of the first resistor, produce a substantially constant voltage across the first transistor which is arranged as a diode. In order to ensure that the current in the second circuit is also stabilized with respect to supply-voltage variations, a second resistor is arranged between the base and the collector of the first transistor, the base of the second transistor being connected to the collector of the first transistor. In the case of a supply-voltage variation, the voltage variation across the first transistor which is arranged as a diode is substantially equal to the voltage variation across the differential resistance of the diode. In order to make the current in the second circuit independent of these last-mentioned voltage variations, the voltage across the differential resistance is compensated for by the voltage across the second resistor.
However, the differential resistance of a diode is inversely proportional to the current through the diode. For a specific value of the second resistor this means that the voltage variation across the second resistor is equal to the voltage variation across the differential resistance for only one specific current and, consequently, one specific supply voltage. The current in the second circuit is therefore independent of supply-voltage variations only to a limited extent. In the case of a suitable value of the second resistor, the known circuit arrangement enables the current in the second circuit to be stabilized to within 5% in the voltage range of approximately 2 to 10 V, which is the customary range for integrated circuits.